1. Materials: The 4 Core “Building Blocks” of a Rigid PCB

• Core Substrate (FR-4): Think of this as the PCB’s “skeleton.” Made by combining fiberglass cloth and epoxy resin, it’s rigid enough to keep the board straight, can withstand temperatures up to 130°C (266°F), and is affordable for mass production. FR-4 is used in 90% of rigid PCBs—from remotes to smartphones—because it perfectly balances “strength” and “cost-effectiveness.”
• Copper Foil: The PCB’s “invisible wires.” Thin copper sheets are bonded to the FR-4 surface, dedicated to transmitting electricity and signals. Basic devices (like remotes) use thinner electrodeposited (ED) copper for good value, while high-power devices (such as power tools) use thicker rolled annealed (RA) copper for more stable transmission and greater durability.
• Solder Mask: The common green coating on the board (sometimes black or blue). It acts as a “protective shield”—preventing copper foil from touching other components (which causes short circuits) and blocking dust, moisture, and scratches. Without it, a single spilled drop of coffee could ruin the entire PCB.
• Silkscreen: The small white text printed on the board, e.g., “R1” or “GND.” Made with heat-resistant ink, it’s like an “installation map” for engineers: helping them place components accurately and quickly locate issues during maintenance.

2. Manufacturing: The 5-Step Process From Design to Finished Rigid PCB

1. Design & Printing: Engineers first draw the PCB layout (e.g., where copper traces go, where components are placed) using software. The design is then printed onto a special “photographic film”—this film acts as a “stencil” for the copper traces.
2. Coating & Exposure: A light-sensitive “photoresist” is applied to the FR-4 substrate. The photographic film is laid over it, and the board is exposed to UV light. This hardens the photoresist in areas where copper needs to stay, while leaving it soft in areas where copper should be removed.
3. Etching: The board is dipped in a chemical solution (e.g., ferric chloride), which “eats away” the soft photoresist and the underlying copper. What remains is exactly the copper traces from the original design.
4. Drilling & Coating: Small holes are drilled into the board to connect components (like chips) to the copper traces. Next, the solder mask is sprayed on and cured with heat. Finally, the silkscreen text is printed and dried.

5. Testing: Each PCB is inspected with machines—checking for issues like broken copper traces or short circuits. Only qualified PCBs move to the next stage, where electronic components are soldered on.
   

3. Functions: Why Most Devices Can’t Live Without Rigid PCBs

1. Connecting Components: Without the copper traces on the PCB, chips, LEDs, and batteries would just be a pile of loose parts. The PCB links them all, allowing electricity and signals to flow—for example, when you press a remote button, the signal travels through the PCB to tell the TV to change channels.
2. Stable Support: The rigidity of FR-4 can hold heavy components (like a laptop’s main chip). Even if the device is bumped, the components won’t shift or fall off. Flexible PCBs can’t do this—they bend under heavy loads.
3. Protecting Parts: The solder mask and FR-4 shield the fragile copper traces from dust, moisture, and high temperatures. For instance, the rigid PCB inside a microwave works safely even when the interior gets hot.
4. Saving Space: Copper traces are printed directly on the PCB, eliminating the need for messy wires. This is why smartphones can be as thin as a credit card—all the “wires” are hidden inside the rigid PCB.

4. Cost: How Much Does a Rigid PCB Cost? 3 Key Factors

1. Size & Complexity: Small, simple PCBs (e.g., for remotes) cost just $0.5–$2 each when ordered in bulk (1,000+ units). Large, complex ones (e.g., 8-layer PCBs for game consoles) can cost $10–$50 each—they use more materials and require more complex manufacturing.
2. Order Quantity: If you only order 10 prototypes, the unit price will be higher ($5–$20 each) because factories charge setup fees. But if you order 10,000 units for mass production, the unit price drops to $1–$5 each—the setup fee is spread out.
3. Material & Quality Requirements: Using standard FR-4 and ED copper keeps costs low. But if you need high-end materials (e.g., heat-resistant FR-4 for car parts) or extra testing (e.g., for medical device PCBs), costs increase by 20%–50%.

Conclusion